Gas-engine.



No. 637,975. Patented Nov. 28, I899. E. RAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.) v 7 (No Model.) 8 Sheets-Sheet l.

No. 637,975. Patented Nov. 28, 1899.

- E. RAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.) (No Model.) 8 Sheets-Sheet 2.

74 v nepfiep In 01970-602" No. 637,975. Patented Nov. 28, I899. E. RAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.)

(No Model nv M502" @5; 1/,

No. 637,975. Patented Nov. 28, I899. E. RAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.) (No Model.) 8 Sheets-Sheet 4.

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No. 637,975. Patented Nov. 28, I899.

E. BAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.]

8 Shasta-Sheet 6.

(No Model.)

(No Model.)

E. RAPPE.

GAS ENGINE.

(Application filed Nov. 1, 1897.) Y

Q I n l Patented my. 2a, 1899.

8 Shuts-sheaf 7.

No.- 637,975. Patented Nov. 28, I899.-

E. BAPPE.

GAS ENGINE.

(Application filed. Nov. 1, 1897.)

(No Model.) 8 Sheets-Sheet 8.

M! E w s s an Mnm%uz NITED STATES PATENT OFFICE.

' EMIL RAPPE, or CHICAGO, ILLINOIS.

GAS-ENGINE.

SPECIFICATION forming part of Letters Patent No. 637,975, dated November 28, 1899. Applicatioii filed November 1, 1397. Serial No. 657,005. (No model.)

To ail whom it may con/cc it:

Be it known that I, EMIL RAPPE, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Gas-Engines; and I do hereby declare the following to be a full, clear,'and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My invention relates to a novel construction in a gasengine, the object being to pro vide a machine of this character which will be particularly adapted for high speed for electric-lighting purposes; and it consists in the features of construction and combinations of parts hereinafter fully described and claimed.

In the accompanying drawings, illustrating my invention, Figure 1 is a front elevation of a gas-engine constructed in accordance with my invention. Fig. 2 is a top plan view of same. Fig. 3 is a vertical section of same, taken on the line 3 3 of Fig. 1. Fig. 4 is a detail sectional view, on an enlarged scale, showing the valve mechanism, taken on the line 4 4. of Fig. 1. Fig. 5 is a horizontal sec tion, on an enlarged scale, on the line 5 5 of Fig. 1. Fig. 6 is a detail sectional view, partially in elevation, on the line 6 6 of Fig. 5. Fig. 7 is a detail sectional view, on an enlarged scale, onthe line 7 7 of Fig. 3. Fig. Sis a detail sectional view, on an enlarged scale, showing the devices for operating the igniters, taken onthe line 8 8 of Fig. 1, the flywheel being omitted. Fig. 9 is a detail view, partially in section, showing the mechanism for operating one of the igniters. Fig. 10 is a detail sectional view, on an enlarged scale, on the line 1010 of Fig. 2. Fig. 11 is a detail sectional View, on an enlarged scale, on the line 11 ll of Fig. 2, showing the inlet-valves. Fig. 12 is a detail sectional View similar to Fig. 4, but on an enlarged scale, some parts being omitted and showing,diagrammatically, the points of opening and closing of the valves.

My invention consists, mainly, in so constructing my gas-engine and so operating the valves as to cause the ignition of an explosive charge alternately in each cylinder, the burned gases to be exhausted, a scavenger charge of air to be introduced to exhaust such mixed air and burned gases, introduce a fresh explosive charge and compress the same, such cycle of operations taking place alternately in each cylinder and requiring four strokes of the piston for each cylinder.

To this end one feature of my invention consists in providing each cylinder with two exhaust-ports, one of which is situated so that it communicates with the combustionchamber only when the piston reaches the lower limit of its movement and the other of which communicates with said cylinder between the upper and lower limits of movement of the piston.

Another feature of my invention consists in providing exhaust valves in said lastnamed exhaust-passage, which are operated by suitable valve mechanism, so as to open at regular relative intervals to effect proper exhaustion of the burned gases.

Another feature of my invention consists in providing inlet-valves on each of said cylinders, which are connected by means of passages with a piston-valve which is operated by means of fluid-pressure and alternately supplies said inlet-valves with fresh air and fresh explosive charges at regular intervals.

Another feature of my invention consists in providing means for utilizing compressed air for starting the engine and for introducing a jet of such compressed air into said cylinders as a scavenging charge at regular intervals, such' means forming part of the valve mechanism.

To these and other ends my engine comprises a frame A, consisting, preferably, of a cast-iron casin g, upon the upper end of which the cylindersB and O are mounted. A crankshaft D is mounted in hearings in the lower end portion of said casingA and is connected by means of pitmen 1 with the pistons 2, moving within said cylinders. Said shaft D also carries a fiy-wheel 3 at one end. Said cylinders B and O are provided with inlet-ports 4 at their upper ends, which are held normally closed by means of spring-actuated valves 5, and with exhaust-ports 6 and 7, the latter of which is controlled by mechanically-operated valves 8 and 9. Said inlet-ports 4 communicate by means of passages 10 and 11 with the piston-valve chamber 12, in which a pistonvalve 13 is mounted, which is normally held at the upper limit of its movement by means 25 sage 20.

jacent said chamber 12, and which is con trolled by means of a spring-actuated valve 17. Projecting into said passage is a nozzle 18, through which compressed air is in- IO troduced for scavenging purposes. Said nozzle 18 projects into said passage 15 beyond the opening 19, establishing communication between the said passage 15 and valve-chamber 16 and is of less diameter than said pas- 5 sage, so as to leave an annular space surrounding said nozzle. Obviously by introducing air under pressure through said noz- .zle the latter will act like an injector-and create a partial vacuum around the same, which will cause the valve 17 to open and admit more air, which is introduced into one of said cylinders as a scavenging charge at one-point of the stroke of the piston. Gas is introduced into said chamber 12 through the pas- Said passage 20 communicates with a gas-supply and is controlled by means of the mechanically-operated valve 21. Said nozzle 18 is connected by means of a pipe 22 with a source of supply of air under pressure,

a three-way cook 23 being interposed in said connection, whereby said compressed air can be deflected either into said pipe 22 or into a pipe 24, communicating with the passage 10,

so as to introduce said air directly into said cylinder B for the purpose of starting the en- Each of said cylinders B and O is provided with a recess 25, in which the ignition is efiected, this being done by means of an electric spark obtained between two electrodes 26 and 27,. consisting of shafts mounted in sleeves 28, mounted in the cylinder-heads and insulated therefrom by means of porcelain sleeves 29 of ordinary design. Said shafts 26 and 27'are provided with enlarged ends, which are adapted to be brought into contact and are provided with serrated contact-faces. The inner ends of the sleeves 29 are ground to form conical valve-seats, in which the conical shoulders formed by the enlarged ends of the shafts 26 and 27 are adapted to be seated like valves, thereby preventing escape of any gases through said sleeves 29. Said shafts 26 are rigid and are so held by means of locknuts 30 on their outer ends,which bear against the outer ends of the sleeves 29, while said shafts 27 are adapted to slide in said sleeves and are normally held at the outer limits of their movement by means of springs 31 being brought into contact with the ends of the shafts 26 by devices operated from the driveshaft. The electric connections are so made as to cause said shafts 26 and 27 to close the circuit when in contact, and thus, by suddenly withdrawing theshaft 27, breaking the circuit and producing a spark. The said gassupply, compressed-air supply, and exhaustvalves and igniting devices are all operated from a rock-shaft 32, mounted in bearings in the frame A and which receives its motion from the crank-shaft D by means of an eccentric 33 on said shaft, which operates an eccentric-rod 34, connected at its other end with a crank-arm 35 on said shaft 32. A sleeve 36 is rigidly mounted on said shaft 32 and is provided with three pairs of parallel arms 37, between which the lower ends of vertical plungers 38, 39, and 40 are adapted to lit, said lower ends of said plungers being provided with slots 41, through which the pins 42 are adapted to extend, by means of which the motion of said arms is transmitted to said plungers. On one of the outer projecting ends of said shaft 32 is an arm 43, provided with an opening through which the rod 44 passes, which operates the igniters. A rock-shaft 45 is mounted in bearings 46 on said cylinders and extends transverselyto and underneath said shafts 27 and carries an arm 47 at one end,whic'h is adapted to be engaged by a pivoted tappet 48 on the upper end of the rod 44, which is adapted to turn in one direction and is rigid in the other direction. A bifurcated arm 49, adjacent said arm 47, is adapted to engage a grooved collar 50 on the shaft 27 of the igniter in cylinder 0 and is adapted to force said shaft inwardly against the action of its spring to close the circuit.

The rod 44 carries a sleeve 51 at its upper end, which moves in a bearing 52 at the end of an arm 53. In the bifurcated upper end of this sleeve 51 said tappet 48 is pivoted. The groove or bifurcation in said sleeve is deeper on the side nearest the arm 47, so that when said rod moves upwardly said tappet can turn out of its path as it comes into contact with said arm 47, and when it has passed the same swing back into its normal position, so that upon a downward movement of said rod 44 it will engage said arm 47, thus turning said shaft 45 and forcing the shafts 27 inwardly to close the circuit. The continued down ward movement of said rod 44 will force said arm 47 out of the path of said tappet 48, and as soon as this has occurred the springs 31 on the shafts 27 will force the latter outwardly, thus causing sparks and returning said arm 47 to its normal position. It will be obvious that it is necessary to provide a yielding pressure against said shafts 27 when the circuit is closed, for the reason that a rigid pressure would have to be constantly readjusted to take up the wear and also for the reason that a rigid pressure would be liable to cause breakage of one of the parts should a mistake be made in the adjustment. To this end I provide two collars 54 and 55 on the lower end of said rod 44, the upperof which is adapted to be engaged by said arm 43, and between the lower of which and said arm 43 a spring 56 is interposed, which is stronger than the combined strength of the springs on the shafts 27 for obvious reasons.

Instead of the bifurcated arm 49 and collar IIO 50 used on the igniter in cylinder 0, I employ an arm 57, loosely mounted upon the shaft 45, which is adapted to abut against the outer end of the shaft 27 in cylinder B to press same inwardly. The said arm 57 is operated from an arm 58, rigid on said shaft 45 and carrying a pin 59, which passes through a slot in said arm 57 and is provided with a collar 60 on its outer end, between which and said arm 57 a spring 61 is interposed which is stronger than the spring on said shaft 27. By turning said shaft 45 in the direction indicated by the arrow in Fig. 9 the arm 58 will obviously contract said spring 61 against said arm 57, and thus turn the same against the action of the spring 31 on said shaft 27, thus forcing the latter inwardly to close the circuit and bringing a yielding pressure against the same during the time that the circuit remains closed.

The plunger 39 is mounted in a bearing 62 in the frame A, and at its upper end carries a head 63, provided with an upwardly-extending lug, to the inner face of which a steel plate 64 is secured, which is adapted to engage a steel plate 65 on the lower end of the arm 66 of a bell-crank lever 67, which is pivotally mounted in a casting 68 on the lower end of a vertical shaft 69, which is mounted and adapted to slide in a bearing 70, mounted midway between the cylinders B and O. The

. other arm 71 of said bell crank lever 67 abuts on its upper face againstthe lower end of a set-screw 72, mounted in said bearing 70, so that as said shaft 69 moves upwardly said bell-crank lever 67 will be turned on its pivot, and thus move the plate 65 out of the path of the plate 64. Said arm 66 of said bell-crank lever 67 carries a lug 73, which enters an opening 74 in said casting 68, which contains a spring 75, adapted to bear against said lug 73 to normally hold said arm 66 in the path of said plate 64. Said shaft 69 is provided with a collar 76 on its upper end portion which is adapted to normally rest upon said bearing 7 O to limit thedownward movement of said shaft. Above said collar 76 said shaft 69 is provided with a slot 77, through which a wedge 78 is adapted to pass, and above said slotted portion said shaft is reduced in size and is journaled in an'opening in an arm 79 of a shaft 80, also journaled in said bearing 70, inwardly of said shaft 69. Said shaft 80 is also provided with a slot 81, through which the small end of said wedge 78 is adapted to pass. Said wedge 78 is mounted upon the end of a shaft 82, slidingly mounted in a hearing 83, pivotally mounted in a bifurcated arm 84 on a rock-shaft 85, journaled in the outer end of said bearing 70. A collar 86 on the outer end of said shaft 82 is adapted to limit the inward movement of the same, and a spring 87 interposed between said bearing 83 and the head of said wedge 78 is adapted to normally hold said wedge at the inner limit of its movement. The lower end of the stem of the valve 21 is rigidly mounted in the upper end of said shaft 80 and is provided with a collar 88 between its ends, between which and the lower end of the valve-casing a spring 89 is interposed, which holds said valve 21 and shafts 80 and 69 normally at the lower limit of their movement. When said rod 39 moves upwardly, the plate 64 will obviously engage the plate 65, which lies in its path, and thus raise said shaft 69. During this movement the bell-crank lever 67 is turned on its pivot, owing to the contact between the arm 71 thereof and the pin 72, and thus gradually moves said plate 65 out of the path of the plate 64. The upward movement of shaft 69 will obviously raise the wedge 78,thus turning the bearing 83 on its pivot. The upward movement of the wedge 78will raise the shaft 80, and thus open the valve 21 to admit gas to cylinders. As soon, however, as the plate 65 has been moved out of the path of the plate 64 by the turning of the bell-crank lever the spring 89 will force the parts raised down again, thus closing the valve 21 and cutting off the gassupply.

The rock-shaft forms a part of the governor which controls the gas-supply, and to this end is provided with an arm 90, connected, by means of a connecting-rod 91, with the arm 92 on a collar 93 on a rock-shaft 94, journaled in a bearing 95 on the outer portion of the frame A, adjacent the fly-wheel. Said collar 93 and a collar 96 on the other end of said shaft 94 are each provided with a downwardly-extending arm 97, carrying inwardlyprojecting lugs 98, which enter the grooved collar 99 on the hub of fly-wheel D. Said collar 99 is slidingly mounted upon said hub and is moved back and forth by the centrifugal throw of a ball-governor of ordinary construction which I employ, but which I have not shown. Obviously as said collar 99 is moved back and forth the shaft 94 will be rocked and the motion thereof will be transmitted to the rock-shaft 85 and thence to the arm 84 in an obvious manner, thus either withdrawing or inserting the wedge 78 into the slots 77 and 81, and thus controlling the extent to which the valve 21 is opened. It will be obvious that as said wedge 78 is gradually withdrawn from the slot 81 the shaft 80, and consequently. the valve 21, is raised later and to a less extent, and the gas-supply thus either partially or entirely out OK should the speed of the engine increase to a great enough extent, said parts being so arranged that the valve 21 is opened for maximum admission of gas when the speed of said engineis lowthat is, said valve opens sooner and remains open for a longer periodand as the speed increases said valve opens later and remains open a shorter time until the point of minimum admission is reached, and thereafter should the speed still increase said wedge 78 is so far withdrawn as to entirely shut off the gas-supply. This I have arranged to prevent waste of gas for the reason that after the point of minimum admission has been passed the mixture of air and gas would be insufficiently rich to ignite, and therefore any gas admitted would be discharged again. By entirely cutting off the gas-supply after the point of minimum admission has been passed raise the same, and thus open said valves,

such intervals of opening of said valves being during the upstroke of said pistons 2. Said plunger 38 carries a lip 101, which is adapted to engage one end of a lever 102, pivotally mounted in one arm of a bell-crank lever 103, pivoted upon said frame A and normally held in the position shown in Fig. 1 by means of the enlargement or weight 104 on the end of the other arm of said bell-crank lever 103. The other end of said lever 102 is adapted to engage the lever end of the stem 105 of an air-valve 106, interposed between said three-way cook 23 and the source of supply of compressed air. Obviously as said lip 101 depresses one end of said lever 102 its other end will engage and raise said valvestem 105, and thus open said valve 106 and admit a charge of compressed air through said nozzle 18, yvhich forms a scavenging charge of air. I propose to start my engine by means ofcompressed air, and to this end I turn said three-way cock 23'so as to cause the air to pass into said pipe 24. I then raise said enlarged end 104 of said bell-crank lever, thus opening said valve 106 and causing compressed air to enter the passage 10, thus introducing pressure underneath the valve 13 and preventing the same from moving and introducing pressure into said cylinder B, which will cause a downward movement of the piston therein and cause said engine to work like a single-acting steam-engine until a charge has been introduced and ignited in said cylinder C. By then dropping said bell-crank lever 103 and turning said cock 23 said scavenging devices will be operated from the rod 38, as hereinbefore described. As before.

stated, said cylinders are each provided with two exhaust-ports 6 and 7, in the latter of which two exhaust-valves 8 and 9 are mounted, by means of which the exhaust from said ports 7 is controlled. Said exhaust-valves 8 are provided with stems 100, which are operated by said plungers 38 and 40, as before stated, while said valves 9 are operated from a lever or beam 107, pivotally mounted in said plunger 39, which engages the lower ends of the stems 108 of said valves 9 at its opposite ends and is adapted to open one or both of said valves 9 at intervals controlled partially by the pressure Within one of said cylinders and partially by the eccentric 33. The gases exhausted through exhaust-port 6 pass directly out of one of the exhaust-pipes 109, while the gases exhausted'through port 7 pass downwardly partially through exhaust-port 6 and partially through the passage 110, thence into passage 111, and thence out of said pipes 109. A back-pressure valve 112 is interposed between said passages 110 and 111 for obvious reasons.

It will be noted that the passage 11 communicates with the chamber 12 about midway between the upper and lower ends of the latter and that the passage 10 communicates with said chamber at its lower end. Said piston-valve 13 is provided with openings 113, which are flush with the passage 11 when said valve is at the upper limit of its movement, so as to establish communication be tween passage 11 and the upper portion of said chamber 12, so that the air and gas can pass directly into said cylinder 0 without any operation of said valve, while the passage 10 is normally shut off. Openings 114 are provided in said valve below said openings 113, which are adapted to be brought flush with said passage 10 when said valve is at the lower limit of its movement. The said valve 13 is operated by fluid-pressure against the action of said spring 14 in the following manner, viz:

The connection between the inlet-valves controlling the gas and air supply, the plum gers 38, 39, and 40, and the eccentric 33 is such and so timed that when the pistons move to the lower limits of their movement and after they have passed said exhaust-ports 7 a partial vacuum is produced in one cylinder, which we will presume to be cylinder B, the explosion causing such movement of said pistons having taken place in cylinder 0. This partial vacuum in cylinder B will obviously cause said valve 5 therein to open, and at the same time also cause said piston-valve 13 to move to the lower limit of its movement, so as to bring the passage 10 into communication with the passage 15 and causing a partial vacuum therein, which will in turn cause said valve 17 to open to admit air. During this part of the stroke a jet of compressed air is admitted through nozzle 18, which is controlled by means of the valve mechanism hereinbefore fully described. This charge of air comprises a scavenging charge adapted to discharge a large portion of the products of combustion which may still remain in said cylinder and is admitted only during approximately the third quarter of the downstroke. During the last quarter of said downstroke, which I will term the second downstroke, a rich gas mixture is admitted to said cylinder. The said exhaust-valves 8 and 9 operate as follows, reference being had to Fig. 12. When the pistons are at the upper limit of their movement, all valves are closed, the eccentric 33 being in the position shown in Fig. 3. During the first half of the downstroke, or until said pistons have passed the exhaust-ports 7, so as to open the same partially, all of said valves remain closed; but directly said pistons have partially opened said exhausts 7 the valve 9 in the cylinder out the products of combustion.

B, for instance, in which the piston is making its second downstroke, opens, the throw of the eccentric being at this time at B, Fig. 12, and having raised the plunger 39 very slightly, thus opening one of said valves 9. It would appear that the lever or beamlO? would open both said valves 9 at the same time. This, however, is not the case, as owing to the high pressure in cylinder C, consequent upon the explosion of the charge therein, the valve 9 therein will be held closed by said pressure, while said valve 9 in cylinder B opens in an obvious manner. During the entire downstroke of said pistons said exhaust-valves 8 in both cylinders remain closed, while the exhaust-valve 9 in cylinder 13 remains open until the piston has again closed exhaust port 7. When said pistons have reached the lower limit of their movement and the pressure in cylinder 0 has been relieved, then said valve 9 in said cylinder C also opens and upon the beginning of the upstroke the valves 8 open, so that during the upstroke of said pistons and until they have closed the ports 7 all exhaust-valves remain open, and consequently during the first half of the upstroke said pistons contin ue to force The opening of the valves for the admission of the scavenging charge of air during the third quarter of the second downstroke in cylinder 13 will obviously cause a rush of air into said cylinder, which causes the expulsion of a further portion of the products of combustion through exhaust 7. A fresh charge of gas is then drawn into said cylinder 13, which remains in the upper end of the same, and upon the second upstroke -of said pistons the remaining products of combustion are expelled until said ports 7 are closed by said pistons, and thereafter said charge in cylinder B is compressed and ignited. The same. operations then take place in cylinder 0, though to admit the scavenging charge of air thereto said valve 13 does not move, as will be obvious.

It will be noted that, as shown in Fig. 3, when said pistons are at the upper limit of their movement the plungers 38 and 40 are in contact with the valve-stem 100 of the valves 8, said valves having just been closed, and are then moved downwardly and out of contact with said valve-stems until said pistons have reached the lower limit of their movement, when said rods will obviously again assume said position, and immediately upon the beginning of the upstroke of said pistons open said valves 8.

I claim as my invention- 1. In a four-cycle gas-engine, two cylinders each provided with an inlet-valve and two exhaust-ports, one of which is located at the limit of the outward stroke of the piston and the other which is located between the latter and the inlet-port, a valve in said last-named exhaust-port, and means for controlling said last-nam ed exhaust-port including the piston, a movable member common to the said valves 3. Inafour-cyclegas-engine,acylinderprovided with an inlet-port, a main exhaust-port, and an auxiliary exhaust-port, a piston movable in said cylinder and adapted to control said main exhaust-port and to partially control said auxiliary exhaust-port, a valve in said auxiliary exhaust-port, and means for operating said valve to open same after the piston has uncovered the main exhaust after a power-stroke and hold it open until the piston has passed said auxiliary port upon its return stroke, and again during the second out and return stroke of said piston.

4. In a gas-engine, two cylinders each provided with two exhaust-ports one of which is controlled by the piston and the other of which is controlled by a valve, and means for operating said valves comprising a lever pivotally mounted upon a moving part of saidengine and engaging the stems of said valves in both said cylinders, said valves being controlled partly by said lever and partly by fluid-pressure.

5. 111 a gas-engine, two cylinders each having an exhaust-port intermediate of the limits of motion of the pistons therein, spring-actuated valves controlling said exhaust-ports, and means for opening said valves alternately in opposite cylinders comprising a lever pivotally mounted between its ends on a moving part of said engine and engaging the stems of said valves at its opposite ends, said lever being adapted to turn on its pivot to open oneof said valves while the other thereof is held closed by the pressure within its cylinder.

6. In a gas-engine, two cylinders provided with inlet-valves, passages leading from said inlet-valves to a valve-chamber, and a valve interposed in said chamber and normally adapted to connect one of said inlet-valves With a source of supply of fluid, said valve bewith inlet-valves, passages leading therefrom to a valve-chamber, passages leading from said Valve-chamber to sources of supply of air and gas, a fluid-pressure valve interposed in said air-supply passage, a mechanicallyactuated valve interposed in said gas-supply passage, and a valve mounted in said valvechamber and adapted to connect said cylinders alternately with said sources of supply of air and gas.

9. In a gas-engine, a plurality of cylinders each provided with an inlet-valve, and connected by passageswith sources of supply of air and gas, and devices interposed in said connection and operated by fluid-pressure for causing said air and gas to enter said cylinders alternately.

10. In a gas-engine, a cylinder, means for introducing and igniting an explosive charge therein, means for exhausting a portion of said products of combustion at the end of the stroke of the piston produced by the explosion of said charge, means for exhausting a further portion of said products of combustion during a portion of the return of said piston, means for introducing a scavenger charge of air during a portion of the third stroke of said piston, means for introducing a fresh explosive charge during the latter part of said third stroke, and means for discharging the remainder of said products of combustion during the fourth stroke or second return stroke of said piston and compressing said fresh explosive charge.

11. In a gas-engine, a cylinder, means for introducing an explosive charge therein, and means for igniting said charge, comprising two electrodes movable endwise with relation to each other and provided at their meeting ends with serrated faces adapted to cause them to revolve slightly with relation to each other when forced into contact, whereby a frictional contact is produced on said meeting faces, and scale formed thereon removed.

12. In a gas-engine, a cylinder and means for introducing a scavenger charge of compressed air thereto at intervals, said means including a valve and devices mounted upon a moving part of said engine for operating the same, connection between said valve and said cylinder independently of said means for introducing a scavenger charge, and means said last-named connection for starting said engine.

13. In a gas-engine, a plurality of cylinders, connections between said cylinders and a source of supply of compressed air, a valve interposed in said connections, devices connected with a moving part of said engine to operate said valve to introduce a scavenger charge of air to said cylinders at intervals through one of said connections, and means common to all of said connections for deflecting the air through any one thereof, said operating devices including a hand-lever for operating said valve to admit air through one of said connections to one cylinder for the purpose of starting said engine.

14. In a gas-engine, devices for introducin g a scavenger charge of compressed air into the cylinders at intervals, and devices for introducing compressed'air into one of said cylinders for starting said engine, said devices comprising a source of supply of air underpressure,connectionsbetween the same and said cylinders, a three-way cock and a valve interposed in said connections for cansin g said air to pass either into the inlet-valve chamber of said engine, or directly into one cylinder independently of said inlet-valve chamber, and a lever pivotally mounted upon a moving part of said engine and adapted to operate said valve at intervals to admit said scavenger supply of air and adapted to be utilized as a hand-lever in connection with said three-Way cock to open said valve to admit a charge of compressed air directly to one of said cylinders for the purpose of starting said engine.

In testimony whereof I affix my signature in presence of two witnesses.

EMIL RAPPE.

Witnesses:

RUDOLPH WM. LoTz, JOHN D. WlLLiAMsoN.

v for introducing said compressed air through 

